Solution:
Mean life of i-pad mini= 10.25 hours
Formula for mean life =
, where d = Time Constant
Mean life of i-pad mini =

Battery life of the i pad mini is uniformly distributed between 8.5 and 12 hours.It can be written as
Pr (8.5 ≤ X ≤ 12)=
, where , d= time constant.